Remove computational bottlenecks in hco_calc_mod.F90

[yantosca]

Name and Institution (Required)

Name: Bob Yantosca
Institution: Harvard + GCST

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• Contributing guidelines

Describe the update

This PR improves the performance of routine Get_Current_Emissions in src/Core/hco_calc_mod.F90. We have refactored code to remove several ELSE blocks following the "never-nesting" coding strategy (see this link for more info.

We have also abstracted some code in Get_Current_Emissions into separate routines both for clarity and for improved computational efficiency.

Expected changes

We have run profiling tests with TAU (Tuning and Analysis Utilities) on the GEOS-Chem carbon simulation using a single CH4 species. The reference simulation, based on 14.2.0-alpha.1, shows that the 2 parallel loops in Get_Current_Emissions are near the top of the list of routines taking the longest time to execute, taking about 22 seconds combined. (See hco_calc_mod_MOD_get_current_emissions_omp_fn.0 and hco_calc_mod_MOD_get_current_emissions_omp_fn.1 in the table below.)

With the updates contained in this PR, we have managed to cut this time down to about 7 seconds:

[yantosca]

I forgot to mention that the above changes were shown to be zero-diff w/r/t 14.2.0-alpha.1:

Using configuration file rst.yml
... Printing totals and differences
... Only showing variables with |absolute difference| > 0.0
Variable               Ref=14.2.0-alpha.1       Dev=hco-cleanup          Dev - Ref

Integration tests are in progress.

[yantosca]

The CHANGELOG.md has also been updated in abaff9a

[yantosca]

All GEOS-Chem Classic integration tests have passed:

==============================================================================
GEOS-Chem Classic: Execution Test Results

GCClassic #c9de6c9 Merge 14.1.1 into dev/14.2.0
GEOS-Chem #d104cebfe Merge 14.1.1 into dev/14.2.0
HEMCO     #e5cf011 Further code cleanup in hco_calc_mod.F90

Using 24 OpenMP threads
Number of execution tests: 26

Submitted as SLURM job: 46051178
==============================================================================
 
Execution tests:
------------------------------------------------------------------------------
gc_05x0625_NA_47L_merra2_CH4........................Execute Simulation....PASS
gc_05x0625_NA_47L_merra2_fullchem...................Execute Simulation....PASS
gc_4x5_47L_merra2_fullchem..........................Execute Simulation....PASS
gc_4x5_47L_merra2_fullchem_TOMAS15..................Execute Simulation....PASS
gc_4x5_47L_merra2_fullchem_TOMAS40..................Execute Simulation....PASS
gc_4x5_merra2_aerosol...............................Execute Simulation....PASS
gc_4x5_merra2_carbon................................Execute Simulation....PASS
gc_4x5_merra2_CH4...................................Execute Simulation....PASS
gc_4x5_merra2_CO2...................................Execute Simulation....PASS
gc_4x5_merra2_fullchem..............................Execute Simulation....PASS
gc_4x5_merra2_fullchem_aciduptake...................Execute Simulation....PASS
gc_4x5_merra2_fullchem_APM..........................Execute Simulation....PASS
gc_4x5_merra2_fullchem_benchmark....................Execute Simulation....PASS
gc_4x5_merra2_fullchem_complexSOA...................Execute Simulation....PASS
gc_4x5_merra2_fullchem_complexSOA_SVPOA.............Execute Simulation....PASS
gc_4x5_merra2_fullchem_LuoWd........................Execute Simulation....PASS
gc_4x5_merra2_fullchem_marinePOA....................Execute Simulation....PASS
gc_4x5_merra2_fullchem_RRTMG........................Execute Simulation....PASS
gc_4x5_merra2_Hg....................................Execute Simulation....PASS
gc_4x5_merra2_metals................................Execute Simulation....PASS
gc_4x5_merra2_POPs_BaP..............................Execute Simulation....PASS
gc_4x5_merra2_tagCH4................................Execute Simulation....PASS
gc_4x5_merra2_tagCO.................................Execute Simulation....PASS
gc_4x5_merra2_tagO3.................................Execute Simulation....PASS
gc_4x5_merra2_TransportTracers......................Execute Simulation....PASS
gc_4x5_merra2_TransportTracers_LuoWd................Execute Simulation....PASS
 
Summary of test results:
------------------------------------------------------------------------------
Execution tests passed: 26
Execution tests failed: 0
Execution tests not yet completed: 0

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%%%  All execution tests passed!  %%%
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